1. Field of the Invention
This invention relates to a recording device such as an output printer of copying device, word processor, facsimile, video, computer, etc. and a substrate for a recording head and a recording head applicable thereto.
More particularly, it relates to a recording head and a recording device to which the liquid jet recording method, which performs recording by discharging liquid for recording through a discharging port, is applicable.
2. Related Background Art
An example of a liquid jet recording head of the prior art is shown in FIGS. 1A and 1B. FIG. 1A is a schematic plan view of the substrate for the recording head. FIG. 1B is a schematic sectional view of the recording head along the line B--B' in FIG. 1A.
The on-demand type recording head of the prior art has an electrode heat converter which generates heat energy to be utilized for discharging liquid (ink) by formation of a heat generating resistance layer 1 comprising HfB.sub.2, TaAl, etc. and an electroconductive layer 2 for formation of electrodes comprising Al, etc. arranged at predetermined intervals formed on a substrate 11 comprising a semiconductor such as silicon or an insulating material such as glass, etc., and on the heat generating portion 1a of the electricity-heat converter are formed a discharging port and a liquid channel communicated thereto. And, a plurality of discharging ports are provided at a ratio of 8 or more per 1 mm for the purpose of high resolution recording, and electricity-heat converters are arranged at high density so as to correspond thereto.
Here, 3, 4 and 5 are protective layers.
The liquid from a liquid vessel, not shown, is supplied into a common liquid chamber forming a part of liquid channel, and further fills the parts containing the heat-acting portions, etc. corresponding respectively to the discharging ports of the channels with liquid.
Recording by way of liquid jetting generates bubbles by causing the state of change in the liquid on the heat-generating portion 1a in the heat acting portion by the heat energy generated from the heat-generating portion 1a by applying recording signals on the electrodes, thereby discharging liquid through the pressure of volume expansion of the bubbles to form flying liquid droplets.
The method for preparation of such recording head of the prior art is to be described.
First, an HfB.sub.2 film 1 as the heat-generating resistance layer for formation of an electricity-heat converter and Al as the electrode 2 are formed by sputtering, etc. and then subjected to patterning.
Next, SiO.sub.2 as the oxidation resistant film 3 for the electricity-heat converter and Ta as the cavitation resistant film 4 are formed by sputtering, etc. and subjected to patterning.
And, a photosensitive polyimide is coated as the ink resistant film 5 and subjected to patterning.
Further, Al, Ni and Cu of the the second layer are subjected to film forming patterning, and Cu is plated to about 10 .mu.m for increasing conductivity to make a common electrode 10. Here, SiO.sub.2 represented by the symbol 3 which the layer beneath the common electrode 10 and the photosensitive polyimide represented by the symbol 5 serve as the interlayer insulating layer.
Then, a ceiling plate 14 having a wall portion for sectionalizing the common liquid chamber 12 and individual liquid chambers 13 as the liquid channels for the recording liquid is plastered and a wiring connected to the driving circuit for supplying electrical signals is electrically connected (not shown) to prepare a liquid jet recording head.
However, in the above prior art example, since the common electrode 10 exists externally of the ceiling plate 14 (namely outside the liquid channel of the recording head), the length of the electrode 2 on the common electrode side is required to be l.sub.2 as shown in FIG. 1A, whereby a considerable length of high density wiring is required at the electrode. For this reason, other than the shortcomings in production such as lowered yield caused by short circuit, wire breaking, etc., short circuit or wire wiring sometimes occurred similarly when driving is performed by passing great currents, whereby durability of the recording head was lowered.